PL193374B1 - Method of obtaining monochromatic images and set of equipment therefor - Google Patents

Abstract

Low silver black-and-white photographic silver halide elements, such as radiographic films, can be processed quickly using black-and-white developing and fixing compositions having reduced photoprocessing activity. The entire process is fairly rapid and effective despite the lowered concentrations of photographic developing and fixing agents.

Description

The present invention relates to a method for obtaining a black and white image and a kit for obtaining a black and white image. The invention relates to photography in general, and more particularly to improved processing of black and white photographic elements. More specifically, it relates to a method for processing low silver black and white films using appropriate developing and fixing steps, and to a processing kit useful for this purpose.

Roentgen discovered X-rays by accidentally exposing a silver-halide photographic element. In 1913, the Eastman Kodak Company introduced its first product specifically designed for X-ray (X-ray) irradiation. Silver halide radiographic films make up the overwhelming majority of medical diagnostic images. It was recognized almost immediately that high-energy ionizing X-rays were potentially harmful, and ways were sought to avoid long-term exposure of the patient. Radiographic films provide visible silver images after image-forming exposure and subsequent processing with immediate access.

One approach, still widely used, is to apply a silver halide emulsion coating useful for radiographic films on both sides of the film substrate. In this way, the amount of X-rays that can be absorbed and used to form an image is doubled, providing greater sensitivity. The Eastman Kodak Company markets double-side coated radiographic films under the trademark: DUPLITIZED films. Films whose operation relies entirely on absorbing X-rays to produce an image are referred to in the art as direct radiographic elements, while films whose operation is to enhance the emission of shielded light are referred to as indirect radiographic elements.

There are other applications for direct radiographic films, such as various industrial applications where X-rays are captured in image formation, but reinforcing screens cannot be used for specific reasons (for piping and turbine blade welds).

The predominant practice is the processing of radiographic films using black and white developing, fixing, rinsing and drying. The movies processed in this way are then ready to be viewed on them.

Black and white photographic developing compositions containing a silver halide black and white developing agent are well known in the photographic art to reduce silver halide grains containing the latent image to produce a developed photographic image. Numerous useful developing agents are known in the art, the most common of which are hydroquinone and similar dihydroxybenzene compounds and ascorbic acid (and derivatives). Such compositions typically contain other ingredients such as sulfites, buffers, anti-fogging agents, halides, and hardeners.

Fixing compositions for radiographic films are also well known and include one or more fixatives, the best known of which are thiosulfates. Such compositions usually contain sulfites as antioxidants.

U.S. Patent Specification US US-A-5,800,976 (Dickerson et al.) Describes radiographic elements with a low silver coating and containing certain compounds to enhance the hiding power of a silver halide emulsion. Such elements are typically processed in conventional developing compositions that include hydroquinone or other dihydroxybenzene compounds.

However, there is a need for less expensive processing compositions with less reactive components, especially for processing low silver components. Additionally, the industry needs a processing method that can provide acceptable black and white images in a short time.

According to the invention, a method for obtaining a black and white image comprising:

A) Development of an exposed black and white photographic element of a silver halide using a black and white developing composition having a pH of 9 to 12 and containing 25 to 200 mmol / l of dihydrobenzene black and white developing agent, 100 to 600 mmol / l sulfite ion, and from 2 to 12 mmol / L additional co-developer, and

B) Fixing the developed black and white photographic element of silver halide with a fixative composition having a pH of 4 to 6 and containing 40 to 120 mmol / l sulphite ions and 250 to 950 mmol / l photographic fixative other than sulphite, whereby the method is carried out for at least 60 seconds, characterized in that a black and white silver halide photo element is used for step A, which has a substrate on both sides of which

A silver halide emulsion unit is applied, containing silver halide grains and a gelatin support, where the silver halide grains contain at least 95 mole% bromide, based on the total amount of silver, and at least 50% of the silver halide grain surface projection is filled with lamellar grains with an average aspect ratio greater than 8, a thickness of not more than 0.10 μm and an average grain diameter of 1.5 to 3 μm, the silver coverage in each unit of _{silver halide emulsion 2} is not greater than 11 mg / dm ² and the coverage of the gelatin carrier in each unit of the silver halide emulsion is no more than 11 mg / dm ² .

Preferably, a black and white developer composition is used which contains a co-developer at a concentration of 2.5 to 7.5 mmol / L, a black and white developer at a concentration of 30 to 90 mmol / L, and sulfite ions at a concentration of 160 to 460mmol / l. Preferably a fixing composition is used which comprises a photographic fixative other than sulfite at a concentration of 300 to 750 mmol / L and sulfite ions at a concentration of 50 to 100 mmol / L; the fixative composition preferably also contains aluminum sulfate in a concentration of 20 to 70 mmol / L. Preferably, cysteine, thiosulfate, thiocyanate or any mixture thereof is used as the photographic fixative. Preferably, both the developing composition and the fixative composition further contain borate ions.

In the process of the invention, silver halide emulsion units are used, each of which preferably contains 0.1 to 0.8% hardener, based on the total dry weight of the gelatin carrier; preferably, the silver coverage in each unit of the silver halide emulsion is from 8 to 11 mg / dm ² and the gelatin-carrier coverage in each unit of the silver halide emulsion is from 6 to 11 mg / dm ² .

In the process of the invention, Step A is preferably carried out for 30 to 60 seconds, and Step B is preferably carried out for 30 to 60 seconds.

According to the invention, the kit for obtaining a black and white image is characterized in that it comprises:

a) a black and white developing composition having a pH of 9 to 12, containing from 25 to 200 mmol / l of black and white dihydroxybenzene developing agent, from 100 to 600 mmol / l of sulfite ions, and from 2 to 12 mmol / l of auxiliary additive co-initiator,

b) a fixative composition having a pH of 4 to 6 and containing from 250 to 950 mmol / l of a photographic fixative other than sulphite and from 40 to 120 mmol / l of sulphite ions,

c) a black and white photographic element of a silver halide containing a substrate on both sides of which is deposited a silver halide emulsion unit containing silver halide grains and a gelatin carrier, the silver halide grains containing at least 95 mole% of bromide, based on the total amount of silver, with where at least 50% of the projected surface area of the silver halide grain is made up of lamellar grains with an average aspect ratio greater than 8, a thickness of not more than 0.10 μm and an average grain diameter of 1.5 to 3 μm, with silver coating in each emulsion unit The silver halide is not more than 11 mg / dm ² , and the gelatin-carrier coverage in each unit of the silver halide emulsion is not more than 11 mg / dm ² .

The present invention discloses a method for efficiently and efficiently processing low silver black and white photographic silver halide elements using less expensive black and white developing and fixing compositions. These compositions contain reduced amounts of photographic processing reagents.

Processing can be carried out in a relatively fast manner due to the combination of a low silver element and particular processing compositions. The element has less than normal silver coating and binding agent, which allows processing compositions to diffuse rapidly into the interior of the element, cause the desired chemical reactions, and remove unnecessary silver with less than normal photographic reagents. This is particularly important for fixation as the lower silver content allows a faster reaction between the photographic fixative and the silver. As the processing time lengthens, it is possible to further dilute the composition. Thus, shorter processing times or processing with more dilute compositions can advantageously be provided. Developing and fixing compositions may also be made into one-part powders, which dissolve readily and provide other benefits.

The present invention is useful for providing a black and white image in a silver halide photographic element, and preferably a low silver silver halide radiographic film. Other types of items that can be processed using the present invention include, but are not limited to, aerial film, black and white camera film, duplicate film and film duplicate film, and amateur and professional constant hue black and white films less coated with silver halide.

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The general composition of such materials is well known in the art, but the specific features that make these materials particularly suited to the present invention are described in more detail below.

The black and white developing composition used in the method of the invention comprises one or more black and white dihydroxybenzene developing agents, including hydroquinone and derivatives thereof, which are readily apparent to those skilled in the art (see, for example, US Pat. A-4,269,929 to Nothangle and US-A-5,457,011 to Lehr et al.). Hydroquinone is the preferred black and white developer. Mixtures of these developing agents can be used if desired.

The black and white developing composition also includes one or more co-developing auxiliaries which are also well known (e.g., Mason, Photographic Processing Chemistry, Focal Press, London, 1975). Any developing auxiliary can be used, but 3-pyrazolidone developing agents (also known as phenidone developing agents) are preferred. Such compounds are described, for example, in US Pat. US US-A-5,236,816 (referenced above). The most commonly used compounds of this group are:

1-phenyl-3-pyrazolidone, 1-phenyl-4,4-dimethyl-3-pyrazolidone, 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone, 4-hydroxymethyl-4-methyl-1-phenyl- 3-pyrazolidone, 5-phenyl-3-pyrazolidone, 1-p-aminophenyl-4,4-dimethyl-3-pyrazolidone, 1-p-tolyl-4,4-dimethyl-3-pyrazolidone, 1-p-tolyl- 4-hydroxymethyl-4-methyl-3-pyrazolidone and 1-phenyl-4,4-dihydroxymethyl-3-pyrazolidone. Other useful co-developing auxiliaries contain one or more solubilizing groups such as sulfo, carboxyl, or hydroxyl groups linked to aliphatic chains or aromatic rings, and preferably linked to the hydroxymethyl functionality of the pyrazolidone as described, for example, in US Pat. US US-A-5,837,434 (Roussihle et al.). The most preferred co-developer is 4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone.

Less preferred co-developers include aminophenols such as p-amino-phenol, o-aminophenol, N-methylaminophenol, 2,4-diamiphenol hydrochloride, N- (4-hydroxyphenyl) glycine, p-benzylaminophenol hydrochloride, 2,4-diamino -6-methylphenol, 2,4-diaminoresorcinol and N- (b-hydroxy-ethyl) -p-aminophenol.

If desired, a mixture of different types of developer auxiliaries can also be used.

It is preferred that the organic anti-fog agent be present in the black and white developing composition, either alone or in admixture. Such compounds control the appearance of total smoke in the processed elements. Suitable anti-fog agents include, but are not limited to, benzimidazoles, benzotriazoles, mercaptotetrazoles, and mercaptothiadiazoles. Representative anti-haze agents include 5-nitroindazole, 5-p-nitrobenzoylaminoimidazole, 1-methyl-5-nitroindazole, 6-nitroindazole, 3-methyl-5-nitroindazole, 5-nitrobenzimidazole, 2-isopropyl-5-nitrobenzimidazole, 5-nitrobenzimidazole , Sodium 4- (2-mercapto-1,3,4-thiadiazol-2-ylthio) butanesulfonate, 5-amino-1,3,4-thiadiazole-2-thiol, 5-methylbenzotriazole, benzotriazole and 1-phenyl-5 -merkaptotetrazole. Benzotriazole is most preferred.

The developing composition also includes one or more safeners or antioxidants. Various traditional black and white safeners can be used including sulphites. Sulfite safener as used herein means any sulfur compound capable of forming or providing sulfite ions in an aqueous alkaline solution. Examples include, but are not limited to, alkali metal sulfites, alkali metal bisulfites, alkali metal metabisulfites, amine sulfur dioxide complexes, sulfurous acid, and carbonyl sulfite adducts. Mixtures of these compounds can also be used.

Examples of preferred sulfites include sodium sulfite, potassium sulfite, lithium sulfite, sodium bisulfite, potassium bisulfite and, sodium metabisulfite, potassium metabisulfite and lithium metabisulfite.

Useful carbonyl bisulfite adducts include alkali metal or amino sulfite adducts with aldehydes and bisulfite adducts with ketones. Examples of these compounds include sodium formaldehyde bisulfite, sodium acetaldehyde bisulfite, bis-sodium succinic bisulfite, sodium acetone bisulfite, b-methylglutaraldehyde bis-sodium bisulfite, butatone bis-sodium bisulfite, and 2,4-pentathione sodium bisulfite.

Various known buffers such as borates, carbonates, and phosphates can be incorporated into the compositions to maintain the desired pH. The pH can be adjusted with a suitable base (such as hydroxide) or acid. The pH of the developing / fixing composition is usually from 9 to 12, more preferably from 10 to 11.

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The black and white developing composition may also optionally include one or more sequestering agents that typically function to form stable complexes with free metal ions (such as silver ions) in solution, in conventional amounts. Many useful masking agents are known in the art, but particularly useful groups of compounds include, but are not limited to, multimeric carboxylic acids as described in US-A-5,389,502 (Fitterman et al.), Aminopolycarboxylic acids, polyphosphate ligands, ketocarboxylic acids. and alkanolamines. Representative masking agents include ethylenediaminetetraacetic acid, diethylene triaminepentaacetic acid, 1,3-propylene diamine tetraacetic acid, 1,3-diamino-2-propanyltetraacetic acid, ethylenediaminodisuccinic acid, and ethylenediaminmonosuccinic acid.

The black and white developing composition may contain other additives including various development weakeners, development accelerators, swelling control agents, and stabilizing agents, each in conventional amounts. Examples of such optional ingredients are given in US Pat. US US-A-5,236,816 (mentioned above), US-A-5,474,879 (Fitterman et al.), And in Japanese Japansese Kokai 7-56286 and European EP-A-0585792.

In the second step B of the process of the invention, a fixative composition comprising a photographic fixative is used to remove the silver. Although sulfite ions exist and sometimes act as a fixative, the initial photographic fixative used in the fixative composition is not sulfite. Rather useful photographic fixatives are selected from thiosulfates (including sodium thiosulfate, ammonium thiosulfate, potassium thiosulfate, and others well known in the art), cysteine (and similar thiol-containing compounds), mercapto-substituted compounds (such as those described by Haist, Modern Photographic Processing , John Wiley and Sons, NY, 1979), thiocyanates (such as sodium thiocyanate, potassium thiocyanate, ammonium thiocyanate and others, well known in the art), amines and halides. Mixtures of one or more of these groups of fixatives may be used upon request. Thiosulfates and thiocyanates are preferred. In some embodiments, a mixture of a thiocyanate (such as sodium thiocyanate) and a thiosulfate (such as sodium thiosulfate) is used. In such mixtures, the mole ratio of thiosulfate to thiocyanate is from 1: 1 to 1:10, preferably from 1: 1 to 1: 2.

The fixative compositions may also include various additives commonly used in this case, such as buffers, fixation enhancers, fixation weakeners, swelling control agents, and stabilizing agents, each in conventional amounts. In its aqueous form, the fixative composition typically has a pH of at least 4, preferably at least 4.5, usually less than 6, and preferably less than 5.5.

The major (and some non-mandatory) ingredients described above are present in the aqueous developing and fixing compositions in the usual and preferred amounts shown in Table I, and all minimum and maximum amounts are approximate (i.e. about). When present in a dry form, developing compositions would mainly contain ingredients in amounts quite obvious to those skilled in the art to produce the desired liquid concentrations.

TABE L A I

Developing composition Usual quantity A favorable amount Dihydroxybenzene developer 25 to 200 mmol / l 30 to 90 mmol / l Co-developing auxiliary agent 2 to 12 mmol / l 2.5 to 7.5 mmol / l Sulphite ions 100 to 600 mmol / l 160 to 460 mmol / l Bromide ions 10 to 50 mmol / l 15 to 45 mmol / l Buffer, e.g. carbonate 100 to 500 mmol / l 100 to 300 mmol / l Tetraborane 0 to 20 mmol / l 6.2 to 17.2 mmol / l Fixing composition Fixing agent other than sulphite 250 to 950 mmol / l 300 to 750 mmol / l Sulphite ions 40 to 120 mmol / l 50 to 100 mmol / l Buffer, e.g. acetate 80 to 250 mmol / l 120 to 180 mmol / l Tetraborane 2.5 to 7 mmol / l 3 to 5 mmol / l Aluminum sulfate 20 to 70 mmol / l 20 to 50 mmol / l

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Black and white developing and fixing compositions useful in the practice of the present invention are prepared by dissolving or dispersing the ingredients in water and adjusting the pH to the desired value. The compositions may also be prepared in concentrated form and diluted to working strength just prior to or during use. The components of the composition may also be prepared in the form of a kit of two or more parts to be combined and diluted with water to the desired concentration and placed in a processing apparatus. The compositions can be used as their own supplements, or other similar solutions can be used as supplements.

Processing may be performed in any processing device or container suitable for the type of photographic item. For example, for radiographic films, the method can be carried out using one or more containers or vessels to perform both developing and fixing steps.

In most cases, the processed element is a sheet of film, but it can also be a continuous element. Each item is immersed in a bath of processing composition for an appropriate period of time in each step.

Development and fixing are preferably followed by, but not essential, a suitable rinsing step to remove silver salts dissolved by fixing and excess fixing agents, and to reduce component swelling. The washing solution may be water, but the preferred washing solution is acidic, and more preferably pH = 7 or less, more preferably from 4.5 to 7, which is suitably provided by a chemical acid or buffer.

After rinsing, the processed items can be dried for the appropriate time and temperature, but in some cases black and white images can be viewed wet.

The processing times and conditions according to the invention are shown in the following Table II, with the minimum and maximum values being approximate (i.e., approximately). The total time for the method of the present invention is typically at least 60 and preferably at least 90 seconds and typically less than 180 and preferably less than 150 seconds.

TABE LA II

PROCESSING STAGE TEMPERATURE (° C) TIME (sec) Invoking 15-30 30-60 Fixation 15-30 30-60 Rinsing 15-30 30-60

The black and white photographic silver halide elements processed according to the present invention typically consist of a conventional flexible transparent film substrate (polyester, cellulose acetate, or polycarbonate) on which each side is deposited one or more photographic silver halide emulsion layers. For radiographic films, it is convenient to use blue tinted substrate materials to produce a bluish-black tint to the image of fully processed films. Preferred film substrates are polyethylene terephthalate and polyethylene naphthalate.

Generally, such elements, emulsions, and layer compositions have been described in many publications, including Research Disclosure, publication 36544, September 1994. Research Disclosure is a Kenneth Mason Publications, Ltd. Dudley House, 12 North Street, Emsworth, Hampshire PO10 7DQ, England.

The emulsion layers contain photosensitive silver bromide with a high silver content, necessary for the formation of the image.

To facilitate rapid access processing, the grains preferably contain less than 2 mol% iodide, based on the total amount of silver. The silver halide grains are mostly silver bromide. Thus, the grains may be silver bromide, silver iodine bromide, silver chlorobromide, silver iodine chlorobromide, silver chlorobromide as long as the bromide is present in an amount of at least 95 mole% (preferably at least 98 mole%) relative to the total silver content.

In addition to the advantages of selecting the compositions described above, it is particularly contemplated to use silver halide grains having a coefficient of variation (COV) of the ECD grains of less than 20%, and preferably less than 10%. It is preferable to use a seed harvest of as much monodispersity as can be conveniently achieved.

Additionally, at least 50% (and preferably, at least 70%) of the silver halide grain surface projection is filled with lamellar grains having an average aspect ratio greater than 8, and preferably

The average grain thickness is usually at least 0.06 and not more than 0.10 µm, and preferably at least 0.07 and not more than 0.09 µm. The average particle diameter is from 1.5 to 3 µm and preferably from 1.8 to 2.4 µm.

Lamellar grain emulsions meeting the requirements of high-bromide grains and gelatin-carrier requirements, except that the gelatin-carrier is fully precured, are described in more detail in the following patents:

Dickerson US-A-4,414,310, Abbott et al. US-A-4,425,425, Abbott et al. US-A-4,425,426, Kofron et al. US-A-4,439,520, Wilgus et al. US-A-4,434,226, Maskasky US-A-4,435,501, Maskasky US-A-4,713,320, Dickerson et al. US-A-4,803,150, Dickerson et al. US-A-4,900,355, Dickerson et al. US-A-4,994,355, Dickerson et al. US-A-4,997,750, Bunch et al. US-A-5,021,327, Tsaur et al. US-A-5,147,771, Tsaur et al. US-A-5,147,772, Tsaur et al. US-A-5,147,773, Tsaur et al. US-A-5,171,659, Dickerson et al. US-A-5,252,442, Dickerson US-A-5,391,469, Dickerson et al. US-A-5,399,470, Maskasky US-A-5,411,853, Maskasky US-A-5,418,125, Daubendiek et al. US-A-5,494,789, OIm et al. US-A-5,503,970, Wen et al. US-A-5,536,632, King et al. US-A-5,518,872, Fenton et al. US-A-5,567,580, Daubendiek et al. US-A-5,573,902, Dickerson US-A-5,576,156, Daubendiek et al. US-A-5,576,168, OIm et al. US-A-5,576,171, i Deaton et al. US-A-5,582,965. Patents to Abbot et al., Fenton et al., Dickerson and Dickerson et al. Are cited to indicate

These include features of a typical element in addition to a gelatin carrier, lamellar emulsion of high-bromide grains and other essential features of the present invention.

The contrast of the film can be increased by adding one or more contrast-enhancing admixtures. Rhodium, cadmium, lead, and bismuth are all well known as contrast enhancers by limiting edge development. Cadmium toxicity precluded its continued use. Rhodium is most commonly used to enhance contrast and is especially preferred. Contrast-enhancing concentrations range from as low as ^10-9 mol / mol of Ag. Rhodium concentrations up to 5 x ^10-3 mol / mol of Ag are particularly contemplated. A particularly preferred concentration of the rhodium dopant is from 1x ^10-6 to 1x ^10-4 mole / mole of Ag.

A number of other dopants are known, alone and in combination, to improve contrast as well as other common properties such as velocity and inverse characteristics. Particularly, dopants capable of providing shallow electron trapping sites, referred to as SET dopants, are envisaged. SET admixtures are described in Research Disclosure, Vol. 367, November 1994, Entry 36736.

Iridium admixtures are very commonly used to reduce the non-reciprocal. For a list of typical admixtures for improving speed, inverse, and other image characteristics, see Research Disclosure, Item 36544, cited above, Section I. Emulsion Grains and Their Preparation, Subsection D.

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Low COV emulsions can be selected from those prepared by conventional batch two-stream precipitation techniques. A general list of silver halide emulsions and their preparation is given in Research Disclosure, Entry 36544, cited above, Section I. Emulsion grains and their preparation. After precipitation and prior to chemical sensitization, the emulsions may be rinsed according to any conventional technique using the techniques disclosed in Research Disclosure, Entry 36544, cited above, Section III. Rinsing the emulsion.

Emulsions may be chemically sensitized according to any convenient conventional technique, as explained in Research Disclosure, Heading 36544, Section IV. Chemical sensitization. Sensitization with sulfur and gold is particularly envisaged.

Both silver bromide and silver iodide have significant natural sensitivity in the blue part of the visible spectrum. Thus, when the emulsion grains contain a high concentration of bromide (> 50 mol%, based on the total amount of silver), the spectral sensitization of the grains is not important, although still preferred. In particular, it is envisaged that one or more spectral sensitizing dyes will be absorbed by the surfaces of the grains to make them or to increase their sensitization to light. Ideally, the maximum absorption of the spectral sensitizing dye is matched (e.g., within ± 10 nm) to the major emission band or bands of the fluorescent enhancement screen. In practice, any spectral sensitizing dye can be used which, when applied as a coating, exhibits a half-peak absorption bandwidth overlapping the major zone (s) of the emission spectrum of the fluorescent intensifying screen that was intended to be used for the first radiographic film.

A large variety of typical spectral sensitizing dyes are known with absorption maximums ranging from the near ultraviolet spectrum (300 to 40 nm), through visible light (400 to 700 nm) to the near infrared (700 to 1000 nm). Particular explanations of common spectral sensitizing dyes are given in Research Disclosure, Entry 18341, Section X. Spectral Sensitization and Entry 36544, Section V. Sensitization and Spectral Desensitization, A. Sensitizing Dyes.

Instability, which increases the minimum density in negative-type emulsion coatings (i.e., fogging), can be prevented by the incorporation of stabilizers, anti-fog agents, anti-refraction agents, latent image stabilizers, and similar additives to the emulsion and adjacent layers prior to coating. Such additions are explained in Research Disclosure, Entry 3654, Section VII. Anti-smoke preparations and stabilizers and Heading 18431, Section II.

Emulsion stabilizers, anti-fog agents and anti-kink agents.

It is also preferred that the silver halide emulsions contain one or more hiding power compounds adsorbed on the surfaces of the silver halide grains. A number of such materials are known in the art, but preferred hiding power compounds contain at least one divalent sulfur atom, which may take the form of an -S- or = S residue. Such compounds include, but are not limited to, 5-mercaptotetrazoles, dithioxotriazoles, mercaptosubstituted tetraazaindens, and others as described in US Pat. US US-A-5,800,976 (referenced above) relating to sulfur-containing hiding power compounds. Such compounds are usually present in concentrations of at least 20 mg / mol of silver, and preferably of at least 30 mg / mol of silver. The concentration may usually be up to 2000 mg / mole of silver, and preferably up to 700 mg / mole of silver.

Again, it is preferred that the silver halide emulsion on each side of the substrate contains dextran or polyacrylamide as water-soluble polymers, which can also enhance hiding power. These polymers are usually present in a weight ratio of at least 0.1: 1 to the gelatin carrier (described above), and preferably in a weight ratio of 0.3: 1 to 0.5: 1 to the gelatin carrier.

The dextran or polyacrylamide may be present in an amount up to 5 mg / dm ² , preferably from 2 to ₂ mg / dm ² . The amount of hiding power compounds on both sides of the substrate may be the same or different.

The silver halide emulsion and the other layers forming the image units on opposite sides of the radiographic element substrate include conventional hydrophilic colloidal carriers (peptizers and binders), which are typically gelatin or gelatin derivatives (referred to herein as gelatin carriers). Typical features of gelatin-carriers and bonded layers are disclosed in Research Disclosure, Entry 36544, Section II. Carriers, carrier fillers, carrier-like additives, and carrier-related additives. The emulsions themselves may contain peptizers of the type specified in Section II mentioned above, paragraph A. Gelatin and hydrophilic colloidal peptizers. Hydrophilic colloidal peptizers are also useful as binders and therefore are usually present in much higher concentrations than required to perform only the peptization function. The gelatin carrier also includes materials that are not themselves useful as peptizers. Preferred gelatin carriers include alkali-treated gelatin, acid-treated gelatin, or gelatin derivatives (such as acetylated gelatin or phthalated gelatin).

To meet the maximum density requirements with minimum silver coverage, the initial hardening of the gelatin carrier should be limited. While it has become standard practice to fully pre-cure radiographic elements containing lamellar grain emulsions, the radiographic elements of the present invention are only partially pre-cured. Thus, the amount of hardener in each unit of the silver halide emulsion is usually at least 0.1% and less than 0.8%, and preferably, at least 0.3% and less than 0.6%, based on the total dry weight. the mass of the gelatin-carrier.

Common hardeners are used for this purpose, including formaldehyde and free dialdehydes such as succinic aldehyde and glutaraldehyde, blocked dialdehydes, α-diketones, active esters, sulfonate esters, active halogen compounds, s-triazines and diazines, epoxides, aziridines, active olefins having two or more active bonds, blocked active olefins, carbodiimides, 3-unsubstituted isoxazole salts, 2-alkoxy-N-carboxydihydroquinoline esters, N-carbamoylpyridinium salts, carbamoyloxypyridinium salts, bis (imonylmethyl) ether salts, especially bis (imonylmethyl) ether salts ) ether, surface-applied carboxyl activating hardeners in combination with complex-forming salts, carbamoylonium, carbamoylpyridinium and carbamoyloxypyrinium salts in combination with certain aldehyde scavengers, dication ethers, hydroxylamine esters of imidic acid salts, and chloroformamide mixed aldehyde hardeners, sy (e.g. mucochloric acid and mucobromic acid), onium-substituted acrolein, vinyl sulfones containing other hardening functional groups, polymer hardeners such as dialdehyde starches and a copolymer (acrolein-methacrylic acid).

In each unit of the silver halide emulsion in the radiographic element, the silver level is usually at least 8 and not more than 11 mg / dm ² , and preferably at least 9 and not more than mg / dm ² . Additionally, the coverage of the gelatin-carrier is usually at least 6 and not more than mg / dm ² , and preferably, at least 7.5 and not more than 9.5 mg / dm ² . The amounts of silver and gelatin carrier on both sides of the support may be the same or different.

The radiographic elements typically include an outer surface coating on either side of the substrate, which is usually used to physically protect the emulsion layers. In addition to the carrier characteristics described above, the outer layers may contain various additives to modify the physical properties of the outer layers. Such additions are explained in Research Disclosure, Item 36544, Section IX. Additives modifying the physical properties of the coating, A. Coating auxiliaries, B. Plasticizers and lubricants, C. Antistatic agents and D. Matting agents. Intermediate layers, which are typically thin layers of hydrophilic colloid, can be used to separate the emulsion layers from the outer surface coverings. It is quite common to include certain emulsion compatible types of external surface coating additives in the intermediate layers, such as anti-matting particles.

Advantageously, the processing method of the present invention may be performed using a processing kit comprising the compositions and processing elements described herein. As a minimum, the processing kit would include a black and white developing composition, a fixative composition, and a silver halide black and white photographic element (one or more samples thereof). The kit can also include a method of application, rinse solution, fluid or composition dispensers, or any other conventional components of a photographic processing kit. All ingredients may be suitably packaged in dry or liquid form in glass or plastic bottles, liquid impermeable packets or vials.

The following example is provided for explanatory purposes and is not considered to be limiting in any way.

Examples of Materials and Methods

A radiographic film (Element A) was produced within the scope of the present invention having the following layering and composition on each side of a polyethylene terephthalate substrate:

PL 193 374 B1

Composition of the outer layer: ₂ Coverage (mg / dm ² ) Gelatin carrier 3.4 Matte methyl methacrylate balls 0.14 Carboxymethylcasein 0.57 Colloidal silica 0.57 Polyacrylamide 0.57 Chromium alum 0.025 Resorcinol 0.058 Lubricant - whale oil 0.15 Composition of the intermediate layer: ₂ Coverage (mg / dm ² ) Gelatin carrier 3.4 AgI Lippmann emulsion (0.08 µm) 0.11 Carboxymethylcasein 0.57 Colloidal silica 0.57 Polyacrylamide 0.57 Chromium alum 0.025 Resorcinol 0.058 Nitron 0.044 Composition of the emulsion: Emulsion of grains-T ₂ Coverage (mg / dm ² ) (AgBr 2.0 x 0.07 μm) 10.6 Gelatine 7.5 4-Hydroxy-6-methyl-1,3,3a, 7-tetraazaindene 2.1 g / mol Ag 4-Hydroxy-6-methyl-2-methylmercapto-1,3,3a, 7-tetraazaindene 400 mg / mol Ag 2-mercapto-1,3-benzothiazole 30 mg / mol Ag Potassium nitrate 1.8 Ammonium hexachloropalladate 0.0022 Maleic acid hydrazide 0.0087 Sorbit 0.53 Glycerine 0.57 Potassium bromide 0.14 Resorcinol 0.44 Dextran P 2.5 Polyacrylamide 2.69 Carboxymethylcasein 1.61 Bisvinylsulfonylmethylether 0.4% of the total amount of gelatin in all layers

The control radiographic element (Item B) was also assessed using the compositions and methods of the present invention. This item is commercially available as a radiographic film

KODAK T-MAT G.

In the Example, the black and white developing and fixing compositions according to the following Table III were used. The pH of the compositions was adjusted by the addition of various acids, bases or buffers.

PL 193 374 B1

TABE L A III

INGREDIENT Comp. Inducing I (mmol / l) Developing comp. II (mmol / l) Developing comp. III (mmol / l) IV inducing comp. (Mmol / l) V inducing comp. (Mmol / l) Fixing Comp. I (mmol / l) Fixative Comp. II (mmol / L) Fixative Comp. III (mmol / L) Fixative IV (mmol / l) Hydroquinone 91 68.2 45.5 31.8 182 0 0 0 0 ELON 0 0 0 0 11.6 0 0 0 0 4- Hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone 7.3 5.3 3.9 2.4 0 0 0 0 0 Sodium sulfite 571 428 285 200 714 120 90 59 42 Bromide potassium 42 32 21 15 42 0 0 0 0 Sodium carbonate 302 226 151 106 500 0 0 0 0 Tetraborane sodium 25 18 12 8.5 0 9.5 7.1 4.7 3.3 Hydroxide sodium 125 95 62.5 45 75 0 0 0 0 Thiosulfate sodium 0 0 0 0 0 950 711 475 332 Sulfate aluminum amo- new 0 0 0 0 0 66 50 33 23 Acid lemon 0 0 0 0 0 15.6 12 7.8 5.7 Sodium acetate 0 0 0 0 0 245 183 123 86 pH 10-11 10-11 10-11 10-11 10-11 4.5-5.5 4.5-5.5 4.5-5.5 4.5-5.5

Example

This example was used to measure the performance of various black and white developing and fixing compositions in accordance with the practice of the present invention.

Samples of radiographic elements A and B described above were exposed to 500 Lux fluorescent lighting for 60 seconds, then processed with various black and white developing and fixing compositions at room temperature as shown in Table IV below. The various sensitometric results [smoke, velocity, contrast, lower scale contrast (LSC) and upper density point (UDP)] have typical meanings, they were measured using standard procedures and are also shown in Table IV.

PL 193 374 B1

T A B E L A IV

Element Compo- an act induce- ca Time triggers- viii (knot) Fixing composition Time fixation (knot) Brawl- no Speed Contrast LSC UDP AND AND 60 AND 60 0.21 440 2.26 2.10 2.69 AND III 60 III 60 0.22 430 1.34 1.96 2.34 AND IV 60 IV 60 0.20 424 1.80 1, 98 2.38 AND IV thirty IV thirty 0.21 410 1, 48 1.89 2.31 B AND 60 AND 60 0.27 427 3.12 2.19 3.62 B III 60 III 60 0.25 419 2.57 2.08 3.24 B IV 60 IV 60 0.20 424 2.47 2.12 2.89 B AND thirty IV thirty 0.52 369 - 1.18 1.96

These results indicate that the weaker the processing chemicals and the shorter the processing time, the less fogging (better fixation) and higher speeds for Element A. Contrast and top density were lower for Element A as its silver coverage was less. Some densities contributing to the higher Dmax and greater contrast in Element B may be due to incomplete fixation.

Claims (10)

1. A method of obtaining a black and white image including: A) development of an imaging, black and white exposed photographic element of a silver halide using a black and white developing composition having a pH of 9 to 12, containing 25 to 200 mmol / l of a black and white dihydroxybenzene developer, 100 to 600 mmol / l of ions sulfites, and from 2 to 12 mmol / L of an auxiliary additional co-developer, and B) fixation of the developed black and white photographic element of silver halide with a fixing composition having a pH of 4 to 6 and containing 250 to 950 mmol / l of non-sulphite photographic fixative and 40 to 120 mmol / l of sulphite ions, the method being for at least 60 seconds characterized in that a black and white photographic silver halide element comprising a substrate is used for step A, on both sides of which a silver halide emulsion unit containing silver halide grains and a gelatin carrier are applied, wherein the silver halide grains contain at least 95 mol% of bromide in relation to the total amount of silver, at least 50% of the projected surface area of the silver halide grain is filled with lamellar grains with an average aspect ratio greater than 8, thickness not greater than 0.10 μm and an average grain diameter from 1, 5 to 3 μm, with the silver coverage in each unit of the ₂ silver halide emulsion not greater than 11 mg / dm ² , and the coverage of the gelatin-carrier in each unit of the silver halide emulsion is not more than 11 mg / dm ² . 2. The method according to p. The process of claim 1, wherein the black and white developer composition is used which comprises a co-developer at a concentration of 2.5 to 7.5 mmol / l, a black and white developer at a concentration of 30 to 90 mmol / l, and sulfite ions in a concentration from 160 to 460mmol / l. 3. The method according to p. The process of claim 1 or 2, wherein the fixative composition comprises a photographic fixative other than sulfite at a concentration of 300 to 750 mmol / l and sulfite ions at a concentration of 50 to 100 mmol / l. 4. The method according to p. The process of claim 3, wherein the fixative composition also comprises aluminum sulfate in a concentration of 20 to 70 mmol / l. 5. The method according to p. The process of claim 1, wherein the photographic fixative is cysteine, thiosulfate, thiocyanate, or any mixture thereof. 6. The method according to p. A process according to any of the preceding claims, wherein the developing composition and the fixative composition also contain borate ions. PL 193 374 B1 7. A method according to claim 7 A process as claimed in any one of the preceding claims, wherein the units of silver halide emulsion are used, each containing 0.1 to 0.8% hardener, based on the total dry weight of the gelatin carrier. 8. The method according to p. The method of claim 1, 2, or 4, or 5, characterized in that a _{silver coating 2} is used, which in each unit of the silver halide emulsion is from 8 to 11 mg / dm ² , and the coating _{2 with a} gelatin-carrier in each unit of the silver halide emulsion ranges from 6 to 11 mg / dm ² . 9. The method according to p. A process as claimed in any one of the preceding claims, wherein step A is carried out for 30 to 60 seconds and step B is carried out for 30 to 60 seconds. 10. A kit for obtaining a black and white image, characterized in that it comprises: a) a black and white developing composition with a pH of 9 to 12, containing from 25 to 200 mmol / l of black and white dihydroxybenzene developing agent, from 100 to 600 mmol / l of sulphite, and from 2 to 12 mmol / l of auxiliary co-developer, b) fixative compositions having a pH of 4 to 6 and containing from 250 to 950 mmol / l of a photographic fixative other than sulphite and from 40 to 120 mmol / l of sulphite ions, c) a black and white photographic element of a silver halide containing a substrate on both sides of which is deposited a silver halide emulsion unit containing the silver halide grains and a gelatin carrier, the silver halide grains containing at least 95 mole% of bromide, based on the total amount of silver, whereby at least 50% of the projected surface area of the silver halide grain is filled with lamellar grains with an average aspect ratio greater than 8, a thickness not greater than 0.10 μm and an average grain diameter from 1.5 to 3 μm, with silver coating in each halide emulsion unit of silver is not more than 11 mg / dm ² , and the coverage of the gelatin-carrier in each unit of the silver halide emulsion is not more than 11 mg / dm ² .